Does anyone have a recommendation for a good book to work from that would be at a level that is more advanced than Japanese for Busy People III? I studied Japanese in college and also went to Waseda and then lived in Japan for a while. But, in terms of local classes (Birmingham UK), the most advanced one just uses the above textbook, which is stuff I already know.

So, any idea what would be good to try? I was considering trying one of the following:

Advanced Japanese: Communication in Context

AN INTEGRATED APPROACH TO INTERMEDIATE JAPANESE

Aozora?

Although at my level most is just a refresher probably - hard to improve after a point if you don't use Japanese every day. I know I learned an insane amount when I lived there but just don't use it hardly at all now!

You might want to take a look at Tobira and An Integrated Approach to Intermediate Japanese.

Most people seem to enjoy Tobira a lot. I have it and have flipped through it, but I'm not done with my beginner's textbook yet. I like the overall structure from what I've seen, and I did a lot of research before buying it.

Get all three; the Basic and Intermediate as well. They are best as a package.

The two I really recommend are William McLure's "Using Japanese: A Guide to Contemporary Usage", and Jay Rubin's "Making Sense of Japanese". Neither are really textbooks in the usual sense; they help you dig into the language.

I agree with the above suggestions. Not sure what the coverage of JBP III has covered but maybe J301 would also be useful. For the JLPT N2 and N1 materials, I would recommend the kanzen master series (the grammar books have been very useful for me). I also agree with jimbreen-san regarding getting the entire set of A ___ Dictionary of Japanese Grammar. I use these 3 regularly in my studies no matter what level I am in.